Control mechanism



Filed Feb. 10, 1951 s Sheets-Sheet 1 Dec. 23, 1952 1.=.,J. MOULTON 2,622,402

-- CONTROL MECHANISM FUEL OFF INVENTOR. QJ 25'"! L,J.Mou1.To-

Dec. 23, 1952 MQULTON 2,622,402

CONTROL MECHANISM Filed Feb. 10, 1951 3 Sheets-Sheet 3 FUEL OFF INVENTOR.

Patented Dec. 23, 1952 CONTROL MECHANISM Lloyd Jackson Moulton, Mentor, Ohio, assignor to The Marquette Metal Products Company, Cleveland, Ohio, a corporation of Ohio Application February 10, 1951, Serial No. 210,345

10 Claims.

This invention relates to an improved control mechanism for internal combustion engine driven electric generator systems and particularly such systems as are used to drive the traction motors of locomotive vehicles, thereby indicating the general object. The invention provides a form of unitary control mechanism for the internal combustion engine and its generator so that notwithstanding large variations in traction motor load or power demand, the engine and generator are enabled to operate efiiciently within safe load limits and at selectable engine and generator speed suited to those variations.

Another object and feature of the invention is the provision of an improved automatically acting engine shutdown control, the operation of which is normally responsive to engine lubricating oil system failures but which is restrained from operating for a sufiicient period to enable routine starting of the engine (e. g. at idling speed) and which also prevents the engine from continuing to operate in the event the lubricating oil system is not functioning properly a predetermined time after starting.

Another object is to provide an improved hydraulically operating, remotely controllable speed setting mechanism for th engine speed governor, which mechanism normally functions to limit the rate at which speed setting adjustment can be effected through remote control while enabling rapid decreased speed adjustments to be effected as required by large changes of speed trolled high strength output motions.

The electro-hydraulic mechanism hereof is adapted to serve the same general purposes as does that of L. J. Moulton application Serial No.

163,115, filed May 20, 1950, entitled Control -Mechanism.

Therein the signal-responsive input motions and combinations are permutatively employed to actuate a hydraulic relay including a pilot valve and servomotor for speeder spring adjustment. Present subject solution avoids considerable expense, and has operational advantages which will be explained, through elimination of the pilot valv and servomotor of the relay and by the use of electric-signal-receiving solenoids which operate simple on-ofi valves to actuate, for example, a pair of plural piston hydraulic slave motor units. .Full stroke operations of the slave motor pistons in turn are permutated through a connected power output member to enable the proper number, sequence and length of speeder spring adjustments necessary for the desired range of speed settings. The strokes of the slave motor pistons are of considerable length and easily adjustable to vary the speeder spring adjustment increments relative to each other within said range with extreme minuteness. The above indicates further objects and special advantages of subject arrangement. Others will become apparent from the following description of the illustrative forms shown in the accompanying drawings, wherein:

Fig. l is a schematic view showing the principal elements of the control mechanism required for safe engine operation by remote control.

Fig. 1A is an enlarged schematic view of an engine shutdown valve.

Fig. 2 is a schematic view showing the governor speed adjusting fluid operated slave motor mechanism only hereof as arranged for actuation by a known type of electric control which is also shown.

Fig. 3 is a sectional, somewhat diagrammatic view of .a form of slave motor control valve adapted for actuation electro-magnetically in a low current circuit.

Fig. 4 is a schematic view showing a modified engine shutdown control system which can be used in place of that shown in Fig. 1.

The invention as shown is particularly adapted for efficiently and safely controlling the loading adjustments of an internal-combustion-enginedriven electric generator for rail locomotive service as a function of engine speed setting, largely through operation of the engine governor in response to speed change detection thereby in accordance with varying power demands of an electric traction motor or plurality of motors supplied with current by the generator.

Governor and general arrangement The engine governor E, as schematically shown particularly by Fig. l, is of the hydraulic relay type having a compensation system enabling isochronous operation. Speed sensing mechanism G of the governor actuates a pilot valve F for causing operation of fuel regulating servomotor H. Speed setting means includes speeder spring J, vertically guided speeder rod K acting thereon and remotely controllable speeder rod adjusting or actuating means including the twin unit fluid operated speed setting slave motor mechanism L, the components of which move in response to energization and de-energization of solenoids A, B, C, and D through operation of respective valves of mechanism L described later. Mechanism L is shown by itself schematically in Fig. 2. The various mechanisms of Fig. 1 are shown in positions occupied when the engine is in operation at idle or starting speed.

The engine governor E, as shown, has its own fluid pressure supply source (pump and accumulator system M) lower right Fig. 1 which source preferably also supplies fluid to the speed setting mechanism L, electrical load control mechanism N (left center, Fig. l) and automatic shutdown mechanisms including a two speed hydraulic motor unit P (upper right) fluid venting or dump valve P and a shutdown valve Q of the governor (lower left) controlled by conjoint action of unit P and valve P as will be shown. In routine shutdown the valve Q is caused to operate in response to decreased speed setting of speeder spring J through speeder rod K beyond idle by a fluid venting or dump valve P" of which a portion of the speeder rod can conveniently be an element.

The fluid pressure supply system M includes pump gears it one of which drives the speed sensing mechanism .G through a lay shaft ll. Main pump and accumulator output line is l2 and all lines continually connected therewith will usually be spoken of as containing governor oil (steady flow). A portion of the lay shaft H forms part of a spurt valve mechanism S (left of governor pilot valve F), which acts continually during governor operation, by causing continuously supplied slot or slots it in the lay shaft to be repeatedly opened and closed in relation to ports IE connected to line 53, whereby to control the rate at which constant pressure governor oil from line 12 is supplied to H3 for use by several parts of subject mechanism including some if not all, of the slave motor components of speed setting mechanism L. During governor operation, the accumulator-connected lines 12a, 12b, and E are subjected continuously to governor oil for rapid action of the mechanisms supplied thereby, and spurt output line [3 is subjected to the same pressure but intermittently to permit slow or controlled movement of the mechanisms it supplies.

For engine safety purposes, provision is made for automatic, engine shutdown in response to engine lubricating oil system failure of two types. Lubrication system failure detector ismechanism T (upper center, Fig. 1). The two-speed hydraulic motor unit P is arranged for actuation automatically by detector mechanism T for accomplishing engine shutdown by control of shutdown valve Q. The operation of motor unit P when called for by detector mechanism T during idle or no load operation of the engine is delayed for routine starting as well as engine testing purposes by being subjected to sp-urtwise fluid from the output line is of spurt mechanism S (spurt fluid shown by interrupted shading in the lines which extend generally around the left side of the diagram through a fluid rate control valve U, upper left).

The fluid rate control valve U acts as a function of increase engine speed setting somewhat beyond that for idle engine operation, as will be explained to substitute continuous flow governor oil, from line [2e for the spurtwise fluid for fast operation of automatic shutdown motor unit P, hence valve Q.

A low engine lubricating oil pressure sensitive (right'hand) motive unit T, of engine lubricatshutdown alarm switch mechanism W (top Fig.

1) includes as its principal element a compound rodX which either by manual operation or by automatic operation of motor unit P works the dump valve P of mechanism W to initiate and terminate operation of shutdown valve Q. Speeder-rod-connected fluid dump valve P has essentially the same action on valve Q for routine shutdown operation.

Governor (Continued) The speed sensitive mechanism G of governor E includes flyballs 20 on a rotary ballhead assembly 2i driven by lay shaft H, the fiyballs and speeder spring J acting on the plunger 23 of pilot valve F in non-rotating pilot valve sleeve 24. Outward action of the'flyballs is opposed by the speeder spring J connected to the pilot valve plunger 2-3 through a thrust plate assembly 25. Speed setting slave motor mechanism L adjusts the speeder spring J to set the engine speed by a succession of direct actions on Speeder rod K. Raising of the rod K results in decreased engine speed settings and lowering of the rod results in increased speed settings.

Hydraulic fluid from output line 12 of the pump and accumulator system M (governor oil) is continually admitted to the relatively smaller piston area ll of the governor servomotor H through continually interconnected output line portions lZa, i213, 20. In the illustrated neutral or equilibrium position or" the governor pilot valve plunger 23, fluid (regulating oil) in line 29 29a is trapped in contact with the larger area side Id of the servomotor piston. Fuel on (rightward) movement of the servomotor piston results from downward pilot valve plunger movement admitting governor oil through ports 28 of pilot valve sleeve 2 to line 29, 29a and the larger piston side 58, and Fuel off (leftward) movement results from upward movement of said valve plunger, thereby spilling trapped regulating oil from line 29 to governor sump through port 30 of the pilot valve sleeve.

Feedback from the governor servomotor to the pilot valve F for isochronous governor operation is a function of servo-action-pumping of compensation fluid through line 32 to and from the working chamber of a receiving compensation piston 33. Piston '33 is attached to the pilot valve plunger 23 by a coil spring M for two-way action on the plunger. pensation fluid is indicated at 35 in line 32.

Shutdown valve mechanism The governor shutdown valve Q, as shown in Figs. 1 and la, is a spring biased, spool-like shuttle plug 35 in a working cylinder or chamber 35a one end of which is connected to governor oil branch E20, the opposite end being connected to a vent line 37 leading to the dump valves P and'P. The chamber between the two ends of plug senormally forms a portion of trapped An adjustable leak-off for comgovernor regulating oil line 29, 29a communicating with the governor servomotor H at its larger piston face. A restricted vent hole 36b through the plug 36 normally equalizes governor oil pressure on the two ends of the plug; but when pressure is relieved in line 31 by the opening of either dump valve P or P the plug moves to the right against the force of the biasing spring 39 until the vent hole is approximately closed by stop 38. The described motion of the plug first closes the line 29 leading from the valve Q to the governor pilot valve F and then vents the trapped fluid through 29a from adjacent the larger side [8 of the servomotor piston causing engine shutdown action as will be apparent. Approximate closure of the vent hole 36?) by stop 38, insures retention of governor oil pressure in the accumulator system for a substantial period of time but due to slight leakage does not interfere with reestablishment of equalized governor oil pressure at the two ends of the plug 36 for enabling the spring 39 to return the plug to its normal position when the dump valve (whichever was opened) has been closed.

Modified shutdown valve mechanism To avoid the possibility of premature depletion of governor oil in the accumulator system during shutdown operation (such as might occur in case the stop 38 of valve Q described above should fail approximately to close the vent hole 36b for any reason) the mechanism according to Fig. 4 may be substituted for valve Q and actuating means for it (i. e. principally dump valves P and P"). In the modified arrangement a piston and valve forming plunger 200 of shutdown valve Q has a biasing spring 20l normally holding the plunger in its illustrated position whereby the governor regulating fluid line 29, 20a is open for normal governor control of the servomotor H. The line 31 and connected ducts normally contain fluid at negligible pressure and the shutdown-demanding operations of valves Pr and Py (corresponding respectively to P and P" of Fig. 1) pressurizes the line 31 to cause movement of plunger 200 to its shutdown-efiecting position (not shown) by which regulating fluid line portion 29 is first closed and line portion 290. is then vented to sump at 205 to cause the governor servomotor to move to engine-shutdown position.

Valve Pa: of automatic and manual shutdown mechanism W is quite similar in arrangement and operation to valve P of Fig. 1 except that normally closed ports 203 and 204 of valve Pa: are suitably connected to governor oil line l2 (accumulator pressure) instead of operating as vent ports as do the corresponding port elements (Ill and H2 more fully describedlater) shown in Fig. 1. Similarly port 206 of speeder-rodoperated valve Py is appropriately connected to accumulator pressure line l2 instead of being a vent port. Ports 203 and 204 are openedby axial movement of rod X in either direction as already described to effect engine shutdown. Port 206 is opened by speeder rod K to accomplish shutdown whenever the speeder rod is raised to its stop position (next above that in which K is illustrated).

After operation of plunger 200 to its shutdown position wherein the governor regulating fluid is spilled said valve has to be returned to its initial position before the engine can be restarted.- To insure such returnof the Plunger 200 the line 31' is vented to sump through a port 201 by a valving edge 201a. of the speeder rod K when the speeder rod is in any other than its stop position. Port 201 communicates through line 208 with a short recess 209 around the shutdown rod X continually connected as by drillings 2I0 with the valve chamber 2 of valve Pm. When shutdown is called for by movement of rod X in either direction the usually then open port 201 is nullified by closing communication between the valve chamber 2 and vent line 208 at 209 before the opening of either port 203 or 204 can cause pressurization of line 31'.

Speed setting mechanism (L) Referring particularly to Fig. 2, subject signal impulse permutation system for stepwise precision adjustment of the speeder spring J by fluid power comprises in part, as shown schematically, a floating differential lever 50 pivotally connected as at a point 5| to the speeder rod K. The pivotal connection need not fasten the parts together but that is preferred arrangement.

The required small incremental speed adjusting movements of rod K result from a combination of stepwise input adjustments at two or more points on the floating differential lever 50. The input adjustments in one direction are effected by action of fluid pressure, and in the return direction preferably by spring means in order to minimize the fluid capacity requirement of the system. A spring 52 around the upper end of the speeder rod K and compressed between a rigid arm K thereof and a block portion (e. g. I 5) of or in the governor casing supplements the force of the speeder spring in supplying the return direction force.

The input adjustments are effected by slave motor units 54 and 55 acting for example on opposite end portions of the floating lever 50 (e. g. unit 54 on effective lever arm 50a which is a whole multiple of the length of the effective lever arm 5% on which unit 55 acts). By movement of each end of such lever 50 into selected ones of four equally spaced positions (spaces greatly exaggerated in Fig. 2) and by selection of the differential lever arm length ratio (e. g.) 50a=twice 50b, permutations of the slave motor movements permit speed setting adjustment of the floating lever pivot point 5| through nine equal increment spaces seven of which (from indicated position 1 to position 8, Fig. 2) are used in the present instance as speed increasing and decreasing steps.

The slave motor unit mechanisms 54 and 55 are preferably exactly alike in construction, hence only one (54) will be described in detail. The solenoid-operated valves 56, 51, 58 and 59 which cause operation of the slave motor elements are also of identical construction. The valves preferably used (typical detail of valve 56 shown in Fig. 3) require only a few one hundredths of an inch of opening and closing movement, and are therefore well adapted for operation either to open or close them by short stroke, low power electro-magnets or solenoids.

Each valve has a biasing spring 60, Fig. 3 (equivalent tension springs shown in Fig. 2) and is solenoid actuated from its normal spring biased position. Three of the valves (56, 5'! and 58) in their normal position vent fluid from respective slave motor cylinders. The fourth valve (59) in its normal position is connected-to. its

:27 cylinder to cause fluid operation of the associ- 'ate'd piston to its -stroke=determiningastop.

Slave motor unit S l -comprises a short stroke displacement element in the form of .a piston tfi operatingly connected as by a push rod-5 to the effective end ofleverarm sta. Pistonlfie is bourneby a longer stroke displacement elemerit (piston 66) the bore 6l ofthe piston 65 serving as theworking cylinder for piston fi. Longer stroke piston fifi slides in acylinder bore 68 of the casing block 15. The push rod GES-may be'guidedby-abushing (not-shown) .or its ends may occupy precision sockets (not shownyin' the lever and short stroke piston 64 or the push rod may be an integral part of the piston (not shown). The type of manufacturing used determines the selection of the :most appropriate design. The top of cylinderboreJB is dead ended generally to close it.

The short stroke piston of .slave .motor .unit is designated is and its cylinder-constituting longer stroke piston l6. Otherwise theparts of :unit 55 are indicated .by the same characters as used'for unit 54.

The strokes of the pistons can be precisionadjusted at each end if desired. However, as shown, the upward short strokes of pistons 64 and M are limited by adjustingscrews it which are accessible through the top of the block #5. Similarly the upward strokes of pistons 55 and 15 are limited by adjusting screwsfitl in he head portions of the cylinders of those pistons. 'As shown in Fig. 2 the adjusting screws so. are threaded sleeves closed bysuitableplugs-Bt for enabling accessibility of adjustment screws -'lt. The downward strokes of the pistons are, for example, limited by snap rings it and 8! as clearly shown.

Subject to precision-adjustment such as described the strokes of piston 6s and i l are (e. g.) one-half the lengths of the strokes of pistons S53 and '56 respectively. Thereby the pistons Bi and Hi can increase and decrease the effective stroke lengths of pistons 65 and/l5 by half the stroke lengths of those pistons. Further each slave piston unit is capable of moving the-connected portions of the lever 553 through three equal spaces or to the four definite floating-leveradjusting positions illustrated. The manner in which the piston strokes and combinations of them operate to obtain the desired precise-speeder adjustment increments will be explained later.

The set of solenoids A, B, andD control respective valves for the slave motor units. The valves 56, iii and till are operated by energization of solenoids A, B, and C (valves on) to admit pressure fluid to the chambers of the respective pistons'from line 53, Fig. 1 (spurtwise flow) and to vent fluid from the chambers (valves oif) when the solenoids aredeenergized as :will be clearly apparent from Fig. 2. Fluid.- from the valves 57 and 58 in their on positions is-admitted directly to the topsof the mahrcylinder bores 68. Fluid from the valve 56 when in on position passes to the. upper end of cylinder: bore 6'! through a hole t'ia or series ofzholes'in the wall of the hollow'piston t6 between its upper and lower lands.

A duct arrangementidentical tothat just described is provided ioradmitting fluid from -;a suitable pressure. source, e. 'g. accun lulator-connected line l2d Fig. 1, to the Working chamber-of short stroke piston it via valve 59,:but, as alreadynoted in reference to Fig.2: the chamber of; piston is vented when its associated valve 'control solenoid .D is energized. jlThat allows routine shutdown action through :the energizationiofa single solenoid. In other words, valve 59 while constructed identically with the other valves is. operated reverselythereofby its connected solenoid so far as causing .on and -off valve operation is concerned. Thus simultaneous energizationof solenoids A and C causes additive actionof the two associated pistons fi i and Bil -for maximum distance of operation of theassociated end of the floating lever but simultaneous energization of solenoids'B and D (valve 5'! on; 59 o'ff) causes asubtractive action of short stroke piston n onthe long stroke of piston '56 in reference tothe floating lever.

Operation of the solenoids controlling the valves-5 6 59 in propersequence for step-'by-step increasenand :decrease speed operationof the engine through the governor is usually accomtplishedby .a manually. operated control drum 84 having a .contaotor plate .of suitable contour. The drum is assumed. to bemoved towardtheleft with respect to. stationary contactsfor increased speed settings of the speeder spring J. The relative position of the various solenoid-connected contacts AB'C'D' and the drum in Figure 1 (all solenoids 'deenergized), results in an idle speed setting. of the'engine. That permits starting. and idling-operation of the engine at times whenthe electrical signal system is disconnected from its, powersource. Fig. 2 shows the stop position of the control drum .84, wherebysolenoid D only is energized in order to position valve 59 forventing fluid from the working chamber of piston '14. In the .stop .position, the. right hand end of the-floating difierentiallever is moved up -to point .D" and the speederrod K. .islif-ted by spring 52 to. its uppermost position in which the dump valve -P operates to vent fluid from line 31- of the shutdown valve .Q to cause engine shutdown.

At the #1, idle speed,. position of the control drum 84 (all solenoids deenergi-zed as already stated) fluid (e.'g.) from governor-accumulatorconnected line IZw-Operates short stroke piston 74 to .bringthe right hand end of the floating lever -5il -to the position designated 00 in Fig. 2, the left hand endof the lever remaining in positio'n OO as illustrated inboth Fig. 1 .and Fig. .2. At the #2 position of the control drum solenoid A only is energized, resulting in movement of the'left end of the floating lever to position A". At #3 position solenoid A is deenergiZedand- C- is energized resulting in associated lever end position C". Simultaneous energization of solenoids A and Cat drum position #4 results in the mutually-additive movement of the two pistons 64 and'BB on the left end of the lever to move it tothe point A".C". In the #5 control. drumv position solenoid C is energized bringing the left hand end of the floating lever 50 touC; solenoid .B is energized causing long stroke downward movement of, piston 16 (right Fig.=2)-..and solenoid D is reenergized causing the inner, piston M to move upwardly (Fig. 2 illustrated position or subtractively relative to the direction of movementof piston 16) so that the right handend of the floating lever is arrested at BD". In the #6 control drum position, solenoid A is energizedin additionto the others which remain energized, causing piston 64 only to movedownwardly in its carrier piston 66 for further lowering of the left end of the floating lever to ATC". The next. position (#7) of the control drum deenergizes solenoidv A permitting piston 64 to move upwardly (subtractively) in its carrier piston 66; deenergizes solenoid D to cause additive movement of piston 14 in piston I6, and solenoid B remains energized as in position #6. The final #8 control drum position energizes solenoid A in addition to solenoids B and C which were energized in the #7 position, whereby the left end of the floating lever is moved from C" to A"C.

Engine lubrication system failure shutdown (automatic shutdown) Referring to Fig. 1, subject system through operation of detector mechanism T automatically effects shutting down of the engine in event (a) the engine lubricating oil system output pressure drops to a predetermined, i. e. dangerously low value in relation to engine speed and (b) the lubricating oil pump intake absolute pressure drops to a predetermined abnormally low'value (excessive pump suction). The lubricating-oil-failure responsive shutdown operation, as already mentioned, needs to be delayed in order to permit routine starting; and the engineer or operator should be enabled to re-start the engine after shutdown and operate it at low speed for brief periods such as will enable study of the cause of lubricating oil system failures.

The lubricating oil failure detector mechanism T acts through a rod 90 to control a valve 9| operable from its normal illustrated position in which its chamber vented at 9Ia into a lowered position (not shown) wherein the vent 9Ia is closed and pressure fluid in a line 92 under control of fluid rate control valve U (upper left) is admitted to the two-speed motor unit P through line 92a. Assuming valve U is in its illustrated position when valve 9| is opened then slow or controlled rate movement of motor unit P results from subjection of its piston 93 to spurtwise fluid from line I3 until the piston 93 moves against its biasing spring 94, comes in contact with the right end of rod X (at adjustables'ection 95 thereof) shifting the rod to the left and opening the dump valve P to cause shutdown action of valve Q. If, instead, the plunger of valve U is lowered to point such as will cut off spurtwise fluid line I3 and open line 92 to governor oil main line I2 then the motor unit P gorks at its high speed rate in initiating shutown.

The working chamber of motor unit P has. to I be vented after'operation of piston 93 thereof into contact with shutdown rod X in order to enable re-starting of the engine after automatic shutdown has taken place since shutdown means (e. g) zero lubricating oil pressure which permits valve 9| to close the vent 9Ia. An adjustable bleeder vent 93a is connected to line 92a to control the rate of piston return. Alternatively the bleeder 93a can be designed to adjust the idle period of the motor P after admission of operating fluid thereto through valve 9| by varying the rate of operating-fiuid-subtractive leakage from the motor chamber.

The fluid rate control valve U, in order to be actuated from its normal low rate (spurtwise) fluid supplying position into high rate supplying position as a, function of all engine speed setting adjustments above a suitable minimum speed, is conveniently arranged as a plunger 96 adjacent speed setting valve unit and having an operating abutment engageable by outer piston 66 of said unit (controlled by solenoid C, Fig. 2) which piston moves downwardly a considerable distance and with considerable force to produce speed setting step #2--#3 as already described. That piston 66 remains in its lowered position for all subsequent increased speed setting steps. The motion imparted to the valve plunger 96 against the return force of its biasing spring 91 is sufficient to enable complete cutting oif of spurtwise fluid at port 96a before port 99b connected to the continuous governor oil line I2 is opened.

Detector mechanism (T) form effective closures respectively for lubricat ing-oil-system connected pressure chamber I02 and lubricating-oil-pump-oonnected suction chamber I03.

Diaphragm I00 of detector mechanism T moves downwardly in response to critically low lubricating oil pressure due to unbalance between the spring device V acting on the upper side of the diaphragm and the lubricating oil pressure acting on the lower side. Equilibrium between spring force and the varying oil pressure is normally substantially maintained by increase and decrease of compression on the spring V in accordance with the positions of the speeder rod K as already noted. The downward motion of diaphragm |0| is resisted by an adjustable spring I04. The described engine shutdown operation through actuation of valve 9| is accomplished through functioning of whichever one of the units T or T detects a failure or undesired condition of the lubricating system. The non-active unit T or T" meanwhile establishes a fulcrum for the lever 98.

It will be apparent from the above that the delay period afforded by admission of spurtwise fluid to the two speed motor P at low speed settings of the governor speeder spring enables the engine to be started by delaying the described shutdown action until normal engine lubricating oil pressure has had time to become established.

Emergency hand shutdown: alarm switch The composite rod X of emergency hand shutdown and alarm switch mechanism W has a manipulatable part, e. g. plunger I98 with an operating knob outside the governor case, by which the rod X may be either pulled out or pushed in manually from its illustrated position in order to work the dump valve P and for reset after automatic or emergency shutdown. Center section IIB of rod X constitutes the plug of valve P which enables venting of line 31 of shutdown valve Q through port III when said section is moved outwardly as by the described automatic shutdown operation or manually and through port I I2 when the rod is moved inwardly or toward motor unit P. Plunger I98 has a one way operating yielding connection (relatively stiff spring H4) with the center section of the rod, the spring preventing the operator from overriding the motor P when piston 93 thereof is in shutdown initiating contact with rod section 95.

When the rod X is moved outwardly by automatic shutdown motor unit P the rod closes an electrical alarm switch IITthrough: abutment of the'rodat IIS With the operating armv l I? of the: switch. Theswitchihas a conventional spring toggle mechanism: (not shown) for" retaining switch arm'II'Iin its "01'1 and off. positions: which incidentally'serves' to hold the rod. in its: illustrated position'and thatoccupied by the rod when automaticshutdown operation has occurred. (rod out'or to the left) In. order :that the operator cannot-damage the switcharm III by emergency hand shutdown performed by inward movement of plunger I08 (switch arm then in off position) the eflecti veabutment between the rod-section l II! andlone side of the switch arm is 'in the form of 'a lighticoilspring I I 8.

The adjustment I between rod sections 95 and IIfl enables variationuof the period of time required by the piston'of motor P, afteropening of valve li'l, in orderfor theipiston tor-cause automatic shutdown, being" thus 'capableofmodiiyingiithe inactivetime' perio'd enabled by varying fluid leakage fronrlines2a through the bleeder 93a.

Electrical load control (mechanism N; Fig. 1)

This hydraulic mechanism, motor I'thereof, through action'of load control valve I26 adjusts the electrical loadingor lo'a'd carrying capacity of the generator (not shown) byvarying-its excitation'r'es'ist'ance I2'I-shown in'the'more-or lesscon-- ventional (i: e. compact) form of an angular-1y adjustable rheostat.

The load control valve I26; the specific opera-- tion ofwhich'will be described later, is adapted for actuation as a combined function of engine fuelregulation by the governor servomotor H and engine speed" setting through the governor (Speeder rod K). The plug I34 ofthe-load control valvaisconnectedby. a link Mil-to an intermediate point I4'I on a floating'lever Hi2; one'end of'whichi is connected as at point' I43 to the speed'er rod K. (e. g. arm K), the opposite'end being" connected at point I i-'4 to linkage M5, I46- arrangecl, in efiect, to be operated in opposite directions by thegovernor servomotor H;

The'load control valve I26 is normally maintained in its illustrated neutral position by the floating lever I 32. For' a given speed setting, change of generator load causes valving motion of" the'load control valve by normal governor fuelregulating servomotion. The load control valve I262 is so: connected; to the lead control motor I25 that action of the motor is such as to counteract the generator load change that has taken place. Motor action (I25) will continue until, through normal governoraction, the governor fuel regulatingservo 'motor'H has returned the load control valve I25 to its neutral position.

In eventof a change in speed setting adjustment (speederr'od'K) valving action of the load control valve I25. will cause, through the load control motor I25; a change of generator loading in' the same direction as the speed change until, through normal action of the governor" fuel regulating servo H, the load'control valve is-returned to its neutral position. Thus for each position of the speed setting mechanismwith a neutral load control valve position there is a corre sponding goverhor fuel regulating servomotor position.

The hydraulic control motor I25 has a rela-- tively' small piston I'25'a continually mechanically' interconnected "with a relatively larger piston I251) by' a toothed pinion I29 meshingwith rack: tooth formations onthe respective pistons to convertthe mutually; reciprocal .motions'or-the" pistonsinto thenecessary angular motion of the rnovableelement of'rheostat I21. One end ofthe smaller piston I25c' is continually connected at I3fl5to governor oil line Itcand the correspondingjend of larger piston 1 I251). is connected by line I3I to the' valve chamber. I33 of the load control valve. I26; The valve plunger we of valve IE6 has lower and upper lands, HEEL-and. I respectively, normally'blockingadmission of operatingfluidito the'working charm-- ber of the larger piston I251) and blocking egress of fluid from the valve chamber tosump;

If "thevalve chamber I 33 is CQIlIltBCtGdIfOI" operation of 'motor. I25-to the .spurt'system. (e; g. line I3. via. I53) that provides. controlled, or

relatively slow, motion ofithe load control motor I25'1in the direction to increase generator excitation without; having to throttle or 'restrictedly orifice any,ofitheiloadcontrol motor fluid lines.

9n the other'han'd" free venting of fluid from the chamber or motor piston 92510 through sump.- lconnected' port thelo'ad control motorin the decreased excitation direction under the action of. governor oil on small. piston 125a. Thereby; the, generator excitation adjustment cannotbe increasedv at suchia'rate aswill endanger the locomotive draft equipment and at the same time deeexcitation.

will be accomplished quickly enough so that (in the absence of interlock between the load control motor and manually. operated electrical .transi-.

tion echanism, seenext heading) the operation will not be apt to damage the switchpoints by closingthem before de-excitation has occurred.

Incidentally, controlledmotion'ofthe load c0n-- troll mechanism It. inv ardecreased' excitation. directicn. can be. accomplished without provision of. line restrictions. by routing. fluid. from vent port L380! 0L load-control-valve I251 through a.

spurt. systemioperating. on. the order oimechanism S.v.hich-..could also. beroperatedrby, shaft I-I.

Transition operation When: the: locomotion electrical system is; de-

signed to enable changing: from' one' type or energizes. a solenoidtitil oftransitiim valve [5i designed temporarily'to. overcome the action oi" fioatinglever' I 32 onthe' load controlivalve- I26 in: the necessary direction to cause decreased excitation: operation: of the load control motor I 25 to' take place; Thepresent' arrangement is one'in 'whichthe transition valve (by solenoid actuated movement offits plug I52) admits governor' oil from line I53i'to a chamber I55 below the load control valve plunger land I35 thus to raise the plunger and dump fluid from the regulating chamberof'load control motor piston I251).

In order that transition operation will not interfere with the normal speed setting and governor fuel. servornotor action through the floating lever M2 the connection at Mt, for example, between the floating lever I62 and" link hi5 c'anfbe made with one way lost motion as illustrated. Suitablev adjustments at points I and IM on the'floa'ting lever I42 can be arranged as iin application Ser. No. 163,115 and for the reasons therein explained;

I3iia enables. rapid travel" of.

stealer I claim:

1. A system for precise step-by-step power positioning of a work element, comprising a set of master valves, each valve being operable to an on and an oil fluid controlling position, a corresponding set of electro-magnetically operating devices and means to energize and de-energize them singly and in combinations for so operating the valves, two slave motor mechanisms each having two pressure responsive displacement members individually controlled by separate ones of the valves and having respective means limiting the motions of the displacement members to difierent length strokes one length being a multiple of the other, one member having a lost motion mechanical connection with its cooperating member such that the valve controlled motions of the two members may be transmitted singly and in combination (in the latter case the motion of the one through the intermediary of the other) and a floating differential lever connected for operation at two spaced points with respective such other slave motor members and at a third point with the work element.

2. A system for precise step-by-step power positioning of a work element, comprising a set of master valves, each valve being operable to an on and an off fluid controlling position, a corresponding set of electro magnetically operating devices and means to energize and de-energize them singly and in combinations for so operating the valves, two slave motor mechanisms each having two pressure responsive displacement members individually controlled by separate ones of the valves and having respective means limiting the motions of the displacement members to different length strokes onelength being a multiple of the other, the member with the shorter stroke having a lost motion mechanical connection with the longer stroke member whereby the valve controlled motions of the two members may be transmitted singly and in combination (in the latter case the motion of the longer stroke member through the intermediary of the shorter stroke member, and a floating differential lever connected for operation at two spaced points with the two shorter stroke members and at a third point with the work element.

3. A system for translating relatively weak electrically transmitted signal impulses into corresponding precise power stroke adjustments of a work element; comprising a floating difierential lever a fixed point on which establishes a pivotal operating connection with the work element for stepwise movement of the element by the lever, two fluid operated motor units each including a power output member connected with the lever at respective points there along such that combinations of relatively equal stroke movements of said points can effect a succession of different length, relatively equal movements of the work-element-connection point, thepower output member of each unit being displaceable by fluid a predetermined definite lever-operating stroke length in respect to a fluid-displaceable carrier for the output member which in turn is guided for a different length lever-operating stroke movement, movements of the carrier being thereby imparted to the lever through the output member, and operating fluid supply means including separate electro-magnetically operated fluid routing valves and displacement chambers controlled thereby for operation of the output members and carrier members.

4. The system according to claim 3 wherein the strokelength of the carrier member of each motor unit is twice the stroke length of the output member thereof.

5. A system for translating electrically transmitted signal impulses into a succession of pre cise approximately equal length power adjustments of a work element; comprising a floating differential lever having pivot establishing means for connection to the work element, two fluid operable mechanisms each including a plural concentric piston and cylinder unit wherein one piston of the unit constitutes a cylinder for another piston thereof, such other piston of each unit being connected to the lever and the connections of the two units being different distances along the lever from the work element pivot-establishing means, one of which distances is a multiple of the other distance, and fluid supply means including an on and oil solenoidoperated valve for each piston of each unit, one piston of each unit having twice the stroke length of the other piston of that unit, whereby each unit is capable of moving its connected portion of the lever into three equally spaced positions.

6. The system according to claim 5 wherein the stroke of the cylinder-constituting piston of each said unit is twice the length of the stroke of the other piston.

7. As a means for operating a floating lever which is pivotally connected to a work element for incremental adjustment thereof in steps, two spring biased piston/cylinder units each comprising a tubular piston serving as a cylinder for a second piston, and a fixed cylinder for the tubular piston; the second piston of the two units being connected to the lever at points spaced different distances from the pivotal connection of the lever with the work element, and a set of electro-rnagnetically operated onoff valves with cooperating duct means arranged to supply fluid individually to the cylinders and to enable exhaust of fluid therefrom.

8. As a means for operating a floating lever which is pivotally connected to a work element for incremental adjustment thereof in steps, two spring biased piston/cylinder units each comprising a long stroke tubular piston serving as a cylinder for a short-stroke piston, and a flxed cylinder for the long stroke piston; the shortstroke piston of the two units being connected to the lever at points spaced different distances from the pivotal connection of the lever with the work element, and a set of electro-magnetically operated on-ofi valves with cooperating duct means arranged to supply fluid individually to the cylinders and to enable exhaust of fluid therefrom.

9. A positioning system for a work element having a point requiring stepwise movement in approximately equal increments, a floating differential lever connected to the work element at said point and having unequal length effective arms and length of one being a multiple of the length of the other, two fluid motor devices for operating the respective arms to produce such incremental motion of the work element, each motor device having a first displacement member acting directly on its associated lever arm and a second displacement member acting on the same arm through the intermediary of the first displacement member, the displacement members of each device having unequal length strokes one a, multiple of the other, and valve mechanism for controlling the operatign; qt, flgid individuallirin. respect to reach displaeementm niberl' positioning systemfora Work element having a point requiring movement stepwise in one direction from astarting po sitionandrmovemerit comparable to at least one step in the opposite direction, all of which movements are initiated electrically transmitted signals; a floatingjdifierential lever connected to the WOIk element atsaid peint,'twc fluid motor devices for operating respective. arms of the lever to produce such? motions of said element in response t reception. of thecsignals, each motor 1'6 device having a first disiilacement membfiriacting direetlyr on its associated leyer. armf'anda second displacement niemberactingbn the same arm through the intermediaryof the first disf placement member, and solenoid operated valves,

10 noidsl LLOYD JACKSON No references cited. 

